轴向往复运动抽油杆柱在弯曲井眼内横向振动的仿真模型

A MODEL FOR THE TRANSVERSE VIBRATION SIMULATION OF SUCKER ROD STRINGS WITH AXIAL RECIPROCATING MOTION IN CURVED WELLBORES

抽油杆柱横向振动的研究是分析油井杆管偏磨现象的基础。该文将定向井抽油杆柱在弯曲井眼内的横向振动问题简化为具有初弯曲的纵横弯曲梁在油管约束下的横向振动问题。除考虑交变轴向载荷对抽油杆柱横向振动的激励外,首次提出弯曲井眼也是轴向往复运动抽油杆柱横向振动的主要激励。综合考虑弯曲井眼对轴向往复运动抽油杆柱横向振动的激励,以及交变轴向载荷对抽油杆柱横向振动的激励,应用弹性碰撞理论描述油管对抽油杆柱横向振动的约束,基于弹性体振动理论建立了具有初弯曲的抽油杆柱在弯曲井眼内的横向振动仿真模型。采用有限差分法与Newmark法实现了对定向井抽油杆柱横向振动的仿真计算。仿真结果表明:仿真结果与现场实际偏磨情况相符,说明在分析抽油杆柱横向振动时,轴向运动导致的弯曲井眼激励是一项不可忽略的因素;算例油井中,杆管偏磨的危险点主要出现在油井的造斜段与抽油杆柱的受压段。该文所建立定向井抽油杆柱横向振动仿真模型可用于指导抽油杆扶正器的优化配置。

The research on the transverse vibration of sucker rod strings(SRSs)is the basis of analyzing the eccentric wear phenomenon between the SRS and the tube string.The transverse vibration of the SRS in the curved wellbore of the directional well is simplified as a transverse vibration problem of a longitudinal-transverse curved beam with initial bending and tube constraints.In addition to the transverse vibration excitation of the SRS caused by alternating axial loads,the curved wellbore is taken as the main transverse vibration excitation for the axially moving SRS for the first time.Based on the elastic body vibration theory,the transverse vibration simulation model of the SRS with initial bending in the curved wellbore is established.In this model,the transverse vibration excitation for the axially moving SRS caused by the curved wellbore and the alternating axial load are considered.The elastic collision theory is applied to describe the tube constraint to the SRS transverse vibration.The finite difference method and Newmark method are used to simulate the transverse vibration of the SRS in the directional well.The simulation results show that the simulation results are consistent with the actual eccentric wear situation in the oil field,and therefore the curved wellbore excitation caused by the axial movement cannot be ignored in analyzing the SRS transverse vibration.And for the example well,the eccentric wear dangerous points between the SRS and the tube string are located in the wellbore deviation section and the SRS compression section.The transverse vibration simulation model of the SRS in the directional well can be used to guide the optimal configuration of sucker rod centralizers.